The Greater Sydney lockdown began on June 26 and almost a month later, New South Wales is recording around 100 new COVID cases a day. We are also seeing the virus spread well beyond the initial eastern suburbs cluster. The virus then spread from NSW to Victoria resulting in a lockdown there too, followed by South Australia. Delta is the most contagious of all variants known. The original Wuhan strain was overtaken by the more contagious D614G strain by March 2020, and that virus was responsible for the Victorian second wave.
Then in September, Alpha emerged in the United Kingdom, and was even more contagious. Alpha seemed set to dominate the world by early 2021, but then Delta emerged and swept the world. It has mutations which make it more contagious than Alpha, and more able to evade the immunity conferred by vaccines. One study found the amount of virus shed from people infected with Delta to be over 1,000 times greater than from the original 2020 strain identified in Wuhan….